In a generally known structure, an optical scanner used for a laser printer and the like has a frame to which a plastic scanning lens is fixed by adhesive.
However, since the scanning lens has a coefficient of linear expansion greater than that of the frame, if the scanning lens of the conventional structure undergoes thermal expansion, for example, under high temperature environment, distortion occurs due to difference between a linear expansion of the scanning lens and a linear expansion of the frame. Accordingly, a lens attachment portion where the scanning lens is fixed to the frame is subject to a load, with the result that the scanning lens may disadvantageously come off the frame.
In view of the above, it would be desirable to provide an optical scanner which can prevent the scanning lens from coming off the frame when the optical scanner is used under high temperature environment.